Firefox 3b5 fastest browser on Mac OS X? Depends on the test

Firefox's latest beta has been reported to be the fastest web browser on Mac …

Yesterday Mozilla posted the last public beta of Firefox, freezing the feature set and working its way toward RC status. Over at ZDNet's Hardware 2.0 blog, Adrian Kingsley-Hughes ran the SunSpider JavaScript benchmark on several versions of Safari and Firefox and declared Firefox 3b5 to be the fastest browser on Mac OS X. Unfortunately, his analysis (and possibly data) are dead wrong.

SunSpider benchmark perfomance, from ZDNet

First, I noticed that Kingsley-Hughes was comparing a beta of Firefox to a stable, shipping release of Safari. So in the interest of fairness (and curiosity), I wanted to compare FF3b5 to the latest WebKit nightly build. And to have a baseline, I included Safari 3.1 in the mix. The tests were run by our resident web-dev extrordinaire Clint Ecker using an Intel Core2 Duo iMac running at 2.16GHz and outfitted with 2GB of RAM. He ran the SunSpider benchmark on Firefox 3b5, Safari 3.1, and the April 1 build of WebKit. The result? Safari 3.1 is still faster than Firefox 3. At running JavaScript.

SunSpider benchmark results, as conducted by Ars Technica

While Kingsley-Hughes found FF3b5 to be about seven percent faster on the benchmark than Safari 3.1, but we found the Safari 3.1 to be 29 percent faster. The WebKit nightly build was slightly faster still, by about 36 percent. This still only proves, however, that Safari is faster than Firefox at running JavaScript. A series of tests on a variety of hardware would prove more conclusively which one is indeed the fastest. At running JavaScript.

What Kingsley-Hughes fails to realize, or at least acknowledge, is that browser speed has more to it than just raw JavaScript performance. Document parsing, DOM-tree building, rendering, and bandwidth and latency are also major factors that contribute to the speed of the browser. Just last month, Apple declared Safari to be the fastest browser based on iBench HTML and JavaScript benchmarks run on Windows.

HTML and JavaScript benchmark results, from Apple

Safari 3.1 is arguably one of the fastest shipping browsers available on both Mac OS X and Windows. The latest beta version of Firefox is definitely a lot snappier on Mac OS X—that is not in question. But a more thorough series of tests will need to be done before declaring any browser to be "the fastest."